SPECIFIC urinary diets for dogs and cats

SPECIFIC has a range of diets with low RSS values supporting the dissolution and prevention of struvite stones and the prevention of recurrence of calcium-oxalate, urate and cystine stones as well as diets for the management of idiopathic cystitis With reduced mineral content and condition appropriate urinary pH.

Urinary Range Shot

Understanding Urolithiasis and Feline Idiopathy

FELINE LUTD

CANINE LUTD

Affects 1-3% of cats a year*
Underlying causes:
Urolithiasis – (accounts for 10-15% of cases of FLUTD*)
Bacterial infection - (5-15%*)
Idiopathic cystitis - (55-70%* **)
Urethal plugs
Anatomical defects
Neoplasia

*iCATcareFLUTD Signs, causes and investigation, http://icatcare.orgJanuary 2017

** He et al. 2022. Prevalence, risk factors, pathophysiology, potential biomarkers and management of feline idiopathic cystitis: an update review. Front. Vet. Sci. 9:900847.

Feline LUTD

Affects 2-3% of dogs a year*
Urinary tract infection (UTI) and urolithiasis are most common causes*
More than 90% of uroliths seen are struvite or calcium oxalate*
For dogs with struvite urolithiasis 95% had UTI as underlying cause*

* Ograin, V.L. 2016 “management of canine lower urinary tract disease” ISVMA

Canine LUTD

Importance of nutrition in managing Lower Urinary Tract Disease (LUTD)

American College of Veterinary Internal Medicine recommended in 2016 that

Uroliths consistent with a composition of struvite should be medically dissolved unless...

Medications or dissolution foods cannot be administered or are contraindicated,
The uroliths cannot be adequately bathed in modified urine
Uncontrollable infection

International Cat Care says of the management of Feline Idiopathic Cystitis:

It has been shown that the best approach to managing cats with FIC is to use multi-modal treatment, making a number of different changes to help reduce the likelihood of recurrent episodes of FIC.

Although drug therapy might be used, and might be helpful in some situations, this is not really a drug-responsive disease

Rather, it is important to concentrate on the diet and the environment, recognising that these aspects have a crucial role to play

The importance of water intake

Increase of water intake and urine volume is beneficial for management of all types of urolithiasis

An increase in water intake is associated with:

Increased urine volume
Reduced urinary concentration
Increased frequency of urination
Reduced urine retention time in the bladder

How to increase water intake?

Feed a wet diet - (contains around 70-80% moisture); even extra water can be added to the wet diet.
Add water to a dry diet (add ≥ 2 times volume of dry diet as water) Introduce additional water gradually to get cat/dog accustomed
Feed a high-sodium diet
- Not recommended in case of concurrent salt-sensitive conditions (reduced heart or kidney function)
- Associated with increased urinary excretion of calcium in cases with calcium oxalate urolithiasis and increased cystinuria in cases with cystine urolithiasis!
- Effect of high sodium intake may only be short-term for period of 3-6 months*
Provide water fountains, additional water bowls or flavoured water (added broth) to increase intake of drinking water of cats (depending on preference of individual cat)

ACVIM consensus: High moisture diets are preferred over high sodium diets *

* Lulich JP et al (2016) ACVIM Small Animal Consensus Recommendations on the Treatment and Prevention of Uroliths in Dogs and Cats. J Vet Intern Med 2016, 30(5):1564-157

Measuring Urine Saturation (RSS)

LOW RSS-VALUE (<1)

Under Saturation

Dissolution

No new crystals form, existing crystals dissolve

MODERATE RSS-VALUE

Metastable Saturation

Metastable Solution

No new crystals form, existing crystals grow

HIGH RSS-VALUE

Super Saturation

Formation

New crystals form, existing crystals grow

Urine saturation is an important factor for crystal formation. RSS provides an objective measure of the likelihood of a urine forming crystals.

RSS looks at urine pH and 12 characteristics of urine including the concentration of Ca, Mg, P, Na, K, ammonium, sulfate, citrate, urate, oxalate, creatinine and chloride. A computer programme then calculates the degree of urine saturation value (=RSS)

The higher the RSS value, the higher the saturation of the urine and so the higher the risk on crystal formation

If the RSS-value is lower than 1 (lower than the solubility product), the urine is undersaturated’ - In the zone of undersaturation no crystals will form and existing crystals will dissolve.
If the RSS-value is in between 1 and the formation product (2.5 for struvite and value 12 for calcium oxalate), the urine is metastable. In this zone no new crystals will form, but existing crystals will continue to grow, and no crystals will dissolve.
If the RSS value is higher than formation product, the urine is called ‘supersaturated’. In this zone new crystals will form spontaneously. Existing crystals will grow, and no crystals will dissolve.

Aim for nutritional management of Urolithiasis

Management of urolithiasis for dissolution and/or reduction of recurrence is aimed at getting undersaturated urine (for dissolution and reduction of recurrence) or urine with metastable saturation (for reduction of recurrence) by:

Reducing urinary concentration of crystal components
An increase in urine volume
Induction of an ideal urine pH

Ideal urine pH and relevant crystal components vary between different types of crystals, but an increase in urine volume is effective in reducing the risk for crystal formation for all types of crystals

MANAGEMENT BY UROLITH TYPE

Struvite Urolithiasis

Struvite - Uroliths

Components: magnesium, phosphorus and ammonium
Struvite crystals form in an alkaline environment
Struvite can be association with urinary tract infections (especially in dogs!!)

Struvite crystal and stones can be prevented and dissolved in an acid environment

Nutritional management of struvite urolithiasis

Cats

Sterile struvite uroliths - Primarily diagnosed in cats

Can be dissolved and its recurrence reduced by feeding an ‘anti-struvite diet’:

Low dietary level of magnesium and phosphorus
Inducing a urine pH < 6.4
Increasing urine volume

For reduction of recurrence of sterile struvite urolithiasis long-term feeding of an anti-struvite diet is required.

Dogs

Infection-induced struvite stones - (primarily diagnosed in dogs)

Can be managed and dissolved by:

Treatment of the infection with antibiotics
Dissolution of stones/crystals by an anti-struvite diet

Once the infection, stones, crystals and clinical signs have disappeared, the reduction of recurrence should be focussed on the prevention of recurrent urinary tract infections (the primary cause of infection-induced struvite urolithiasis). Regular monitoring for the presence of UTI’s (by urine culture) is recommended.

In contrast to sterile struvite stones, it is not recommended to continue long-term feeding of an anti-struvite diet for reduction of recurrence of infection-induced struvite urolithiasis

Calcium oxalate urolithiasis

Components: calcium, oxalate
Oxalate is metabolised from the amino acid glycine
Two types of calcium oxalate crystals:
- mono-hydrate (dumbbell / oval shape)
- dihydrate (envelope / octahedral shape)

The urine pH does not affect the solubility of Ca-oxalate, but acid urine is associated with increased calcium excretion in the urine

Calcium oxalate can not be dissolved!

The incidence of calcium oxalate increases with age. In dogs, the incidence is higher in males and some breeds (Schnauzers, Terriers, Maltesers, Shih Tzus) are more prone to develop calcium oxalate.

The aetiology of calcium oxalate is still not completely clear, but hypercalciuria seems to play an important role.

Calcium oxalate can form

At high urinary concentrations of calcium and oxalate
Especially at low urine pH (associated with increased excretion of calcium in the urine)
At low concentration of inhibitors (e.g. citrate) or presence of promotors (e.g. uric acid)

Calcium oxalate stone formers often have underlying causes (hypercalcemia, hyperparathyroidism, distal renal tubular acidosis, absorptive hypercalciuria, renal calcium leakage)

Nutritional management of calcium oxalate urolithiasis

As calcium oxalate cannot be dissolved, nutritional management is focused on reduction of recurrence.

Reduce dietary protein level
- Less intake of glycine which can be metabolised into oxalate
- Protein reduction is associated with reduced urinary calcium and increased urinary citrate concentration
Urine pH at 6.5-7.5 (to prevent high urinary Ca excretion at low urine pH)
Low sodium (high sodium intake increases urinary Ca excretion)
Add potassium citrate (citrate keeps calcium in solution and potassium citrate can increase urine pH)
Increase urinary volume

A role for omega-3 fatty acids from fish oil (EPA & DHA) in the reduction of recurrence of calcium oxalate?

In a study* with healthy cats, supplementation of a control diet with fatty acids (0.1% arachidonic acid, 0.09% EPA and 0.18% DHA):

Decreased urine specific gravity, urinary calcium concentration and RSS for struvite
Increased the resistance to calcium oxalate formation

Also in a review of human studies **, supplementation with polyunsaturated fatty acids, especially EPA and DHA, was frequently associated with reduced urinary calcium and oxalate concentration and it reduced calcium oxalate nephrolith recurrence in a study with stone formers

* Hall JA, Brockman JA, Davidson SJ, MacLeay JM, Jewell DE (2017) Increased dietary long-chain polyunsaturated fatty acids alter serum fatty acid concentrations and lower risk of urine stone formation in cats. PLoS ONE 12(10): e0187133. https://doi.org/10.1371/journal.pone.0187133

** Rodgers AL & Siener R (2020) The efficacy of polyunsaturated fatty acids as protectors against calcium oxalate renal stone formation: a review. Nutrients 2020, 12, 1069; doi:10.3390/nu12041069

Urate urolithiasis

Ammonium urate, sodium urate and uric acid urolithiasis
Common component: urate
Urate crystals form in acid urine, when there is a high urinary concentration of urate.

Ammonium urate crystals can be dissolved.

Urate in urine is metabolised from purines (nucleotides which are present in DNA), derived from endogenous protein and from the diet (especially protein sources as meat and fish are rich in purines)

In normal healthy dogs, purines are metabolised in the liver into allantoin (which is well soluble).

Urate stones are found more often in Dalmatian dogs and English Bulldogs and in dogs with portosystemic shunts or liver disease.

In Dalmation dogs, and dogs with liver disease or hepatic shunts, purines are not completely metabolised into allantoin, but into urate, which is less soluble, especially not in an acid environment

Nutritional management of urate urolithiasis

Nutritional management for dissolution of urate stones and reduction of recurrence is aimed at:

Reduction of dietary intake of purines by:
- Reduction of the protein level (source of purines and ammonium)
- Use of low purine raw materials such as eggs and rice
Induction of a urine pH of 6.5-7.5 for better solubility of urate
Increasing urine volume is beneficial

Cystine urolithiasis

Cystine – a sulphur containing amino acid (which can also be metabolised from methionine)
Cystine crystals are flat, colourless hexagonal crystals – microscopically they can easily be overlooked at high light intensity
Cystine stones are not always visible on regular X-rays and diagnosis may require contrast radiography or ultrasonography
Cystine urolithiasis is the result of a hereditary defect in the renal tubular reabsorption of cystine from the pre-urine.
Cystine urolithiasis is more frequently found in males; predisposed breeds are English Bulldogs, Dachshunds, Mastiffs, Newfoundlands, Staffordshire Bull Terriers.

Cystine crystals form in acid urine and can be dissolved.

Nutritional management of cystine urolithiasis

Nutritional management for dissolution of cystine stones and reduction of recurrence is aimed at:

Reduction of dietary protein to reduce intake of sulphur-containing amino acids cystine and methionine
Induction of a urine pH of 7.5 for better solubility of cystine
Increasing the urine volume
Avoiding high sodium intake as this can increase cystinuria

Supply of sufficient taurine and L-carnitine is recommended (as cats/dogs produce taurine and L-carnitine from methionine)

Mixed Stones

Uroliths can contain 2 or more different type of crystals

Mixed stones often have a center composed of one type of crystal surrounded by an outer layer composed of another type of crystal

Mixed stones can generally not be dissolved and need to be removed by surgery

Prevention of recurrence should be targeted to the type of crystal in the center (=initial cause)

Importance of nutrition in managing feline idiopathic cystitis (FIC)

International Cat Care says of the management of Feline Idiopathic Cystitis:

It has been shown that the best approach to managing cats with FIC is to use multi-modal treatment , making a number of different changes to help reduce the likelihood of recurrent episodes of FIC. Although drug therapy might be used, and might be helpful in some situations, this is not really a drug-responsive disease.

Many drugs may initially appear to work, because the clinical signs tend to resolve spontaneously in most affected cats, but long term studies have suggested few, if any, drugs have any real impact on this disease Rather, it is important to concentrate on the diet and the environment, recognising that these aspects have a crucial role to play.

Aim for nutritional management of feline idiopathic cystitis (FIC)

Aim of the management of FIC is to reduce the severity and frequency of recurrence of episodes of clinical signs.

Multi-modal treatment

Multi-modal treatment of feline idiopathic cystitis (FIC)

Optimal management is multi-modal treatment, which includes:.

Multimodal environmental modification (MEMO) to reduce stress
Medication
Analgesic, anti-inflammatory and or antispasmodic drugs
Feline facial pheromones and other drugs to reduce stress
Nutritional management

Multimodal environmental modification

Multi-modal environmental modification

MEMO is considered the major therapy for FIC and is based on:

Creating a safe place for the cat (places to hide, elevated locations)
Predictable routine
In multi-cat households: multiple litter boxes, feeding and drinking bowls (more than 1 per cat)
Toys, food puzzles
Social interaction and playing with owner
Clean litter boxes (on each floor) with the right grit for the cat
Scratching posts
Pleasant smells, limiting noise

* He et al. 2022. Prevalence, risk factors, pathophysiology, potential biomarkers and management of feline idiopathic cystitis: an update review. Front. Vet. Sci. 9:900847.

The importance of nutrition in multi-modal treatment

Nutritional management plays an important role in the multi-model treatment of FIC:

Feed a wet diet and/or increase water intake In a prospective study, 54 cats with FIC were fed either a wet or a dry diet for a period of 1 year. 11% of the cats which were fed a wet diet had recurrent episodes of FIC, which was significantly lower than 39% of the cats fed a dry diet*
Glycosaminoglycans (GAGs) Cats with FIC have lower urinary concentrations of GAGs and a thinner natural protective GAGs layer coating the bladder wall. In a controlled, double-blinded study, supplementation with glucosamine for 6 months did not reduce recurrent episodes of FIC versus the control group. Howeve in individual cats, beneficial effects of GAG supplementation were reported. **
Omega-3 fatty acids EPA & DHA FIC is associated with inflammation in the bladder and increased serum levels of inflammatory cytokines. As omega-3 fatty acids EPA & DHA can help support the body’s natural anti-inflammatory processes, it is hypothesized that increased intake of EPA and DHA will have a beneficial effect on cats with FIC. There are no controlled studies to proof this yet.

*Markwell JP et al. (1999) Clinical evaluation of commercially available urinary acidification diets in the management of idiopathic cystitis in cats. JAVMA 214 (3): 361-5

** Gunn-Moore DA, Shenoy CM (2004) Oral glucosamine and the management of feline idiopathic cystitis. JFMS 6: 219-225.

The Role of Nutrition in Managing Lower Urinary Tract Disease

This course covers the effects of lower urinary tract disease and nutrition conversely with reference to immediate and long terms diets.

Already registered for the Dechra Academy? - go directly to the course:

Access the module on managing Lower Urinary Tract Disease

Dechra Academy The Role of Nutrition in Managing Allergies and Atopic Dermatitis

The Dechra academy provides a range of on-line learning including this course related to urinary disease

SPECIFIC Diets for the nutritional management of urolithiasis and feline idiopathic cystitis (FIC)

SPECIFIC DIETS FOR THE NUTRITIONAL MANAGEMENT OF UROLITHIASIS
	AIM	FOR DOGS	FOR CATS
Struvite	Dissolution*	CCD - Struvite Management	FCD, FCD-L , FCW & FCW-P Crystal Management & FSW - Struvite Dissolution
	Reduction recurrence**	CCD - Struvite Management	FCD, FCD-L , FCW & FCW-P Crystal Management
	Reduction recurrence - overweight		FCD-L Crystal Management Light FRD Weight Reduction
Calcium Oxalate	Reduction recurrence	CKD & CKW Heart & Kidney Support	FKD, FKW & FKW-P Kidney Support
Urate	Dissolution & Reduction recurrence	CDD Food Allergen Management CKD & CKW Heart & Kidney Support	FKD, FKW & FKW-P Kidney Support
Cystine	Dissolution & Reduction recurrence	CKD & CKW Heart & Kidney Support	FKD, FKW & FKW-P Kidney Support

* Struvite urolithiasis in dogs is almost always secondary to a urinary tract infection (UTI). Use of antibiotics are essential for the dissolution of infection-induced struvite uroliths.
** For reduction of recurrence of canine infection-induced struvite urolithiasis monitoring for UTIs is most important. In contrast to sterile struvite urolithiasis in cats, long-term feeding of an anti-struvite diet is not required for reduction of recurrence of canine infection-induced struvite urolithiasis

DIETS FOR THE MANAGEMENT OF FELINE IDIOPATHIC CYSTITIS
Feline Idiopathic Cystitis	FCW & FCW-P Crystal Management FXW & FXW-P Adult If there is any suspicion of struvite crystals or a history of urolithiasis or urethral plugs then FCW/FCW-P is preferred over FXW/FXW-P

SPECIFIC Urinary Diets - FAQ's

What diet is recommended for cats with ammonium urate urolithiasis?

Ammonium urate urolithiasis is promoted by high concentrations of ammonium and urate in the urine and a low urine pH. In healthy animals, purines (from DNA) are converted into allantoin. In animals with impaired liver function or liver shunt, purines are not converted to allantoin, but to urate. In cats, however, the cause is usually unknown. The production of acidic and concentrated urine, combined with a diet rich in purine (for example, liver) is described as cause.

The guidelines for a diet for solution and prevention of ammonium urate are the following:

The use of low-purine raw materials, such as eggs, milk products and rice.
A low protein content in the diet to reduce the supply of purines and a decrease in the ammonium content in the urine.
The induction of a urinary pH in the range of 6.5-7.5 to promote urate solubility.

In addition to the above-mentioned specific guidelines for the prevention of urate formation, the general advice is to prevent crystal formation by giving the cat plenty of water through the diet. This will increase the urine volume and make the urine less concentrated. Increased water absorption can be achieved by giving the cat a wet food (canflex / pouch) or by soaking dry kibbles in water. Giving a wet food will increase the water absorption the most, especially if some extra water is mixed with the wet food.

The diets we recommend for ammonium urate urolithiasis in cats: SPECIFIC FKD / FKW / FKW-P

SPECIFIC Kidney Support (FKD / FKW / FKW-P) can be prescribed to dissolve and prevent recurrence of ammonium urate stones in cats. These diets are not exclusively made from low-purine raw materials, but due to the reduced protein content and the induction of a higher urinary pH, they are suitable for the prevention of urate stones.

It is recommended to monitor regularly for urine pH, specific gravity, presence of crystals, urinary tract infection and any new stones. The guideline is to keep the specific gravity of the urine below 1.030 and the urine pH between 6.5 and 7.5. If the cat's urine pH is too low, potassium citrate can help make the urine more alkaline. Starting dose is 2 times 50-75 mg / kg BW (2 weekly monitoring and pH guided adjustment is desired).

Since urate stones are often caused by hepatic impairment, it is recommended to monitor the liver function of the cat. In addition to diet, allopurinol can be given in animals with recurrent urate stones, but this is not common in cats.

What diet can be recommended for a cat with urinary struvite and urate crystals?

First of all, it is important to note that the presence of struvite in cat urine is not alarming. Also in healthy cats without urinary tract problems, struvite crystals can be present in the urine. It will only become alarming when there are many struvite crystals and when they form aggregates.

Presence of crystals cannot be considered as a disease. Struvite crystals are present in urine of both stone formers and non-stone formers (Carbone M.G. Phosphocrystalluria and urethral obstruction in the cat. J. Am. Vet. Med. Assoc 1965: 147: 1195-1200). Apparently, the development of struvite urolithiasis not only depends on the presence of struvite crystals, but there are several interrelated complex physiologic and pathogenic factors involved (such as presence and/or absence of inhibitors and promotors of crystal precipitation and aggregation). As also stated by Allen and Kruger: ‘Detection of crystalluria does not mean a cat will subsequently develop urolithiasis. Crystalluria that occurs in cats with normal anatomy and physiology of the urinary tract is usually of no clinical significance (Allen T.A. & Kruger J.M. Feline Lower urinary Tract Disease in: Small Animal Clinical Nutrition (Eds Hand, Thatcher, Remillard and Roudebush), 2000, Mark Morris Institute).

The presence of struvite crystals could the results of a urinary tract infection. It is therefore recommended to check for this.

The presence of urate crystals in cats is rather rare, so it is therefore recommended to direct the nutritional management on the reduction of urate urolithiasis. Urate crystals can only precipitate when the urine is acid and they are often formed as a result of liver disorders. It is recommended to check what diet the cat is currently fed and if it has any liver problems.

For the prevention of urate urolithiasis SPECIFIC FKW Kidney Support is recommended. Since this is a wet diet, it will induce a more diluted urine and will thereby reduce the risk on any kind of urolithiasis. Since this cat also had a history of pee-ing in the house, it could also suffer from idiopathic cystitis. Also for idiopathic cystitis a wet diet is recommended. It is recommended to try to mix even somewhat more water through the FKW in order to increase the water intake and to reduce the urinary tract problems even further.

What diet is recommended for cats with calcium oxalate urolithiasis?

Calcium oxalate urolithiasis is promoted by high concentrations of calcium and oxalate in the urine. Existing calcium oxalate stones cannot be dissolved and must be surgically removed. A diet is recommended to prevent recurrence.

The guidelines for a diet to prevent calcium oxalate in cats are the following:

A low protein content in the diet, because the amino acid glycine is a precursor of oxalate.
An induction of a urine pH between approx. 6.5 and 7.5 because an excessively acidic urine could cause calciuria.
Low sodium in the diet to prevent calciuria.

In addition to the above-mentioned specific guidelines for the prevention of calcium oxalate formation, the general advice also applies to counteract crystal formation by giving the cat plenty of water through the diet. This will increase the urine volume and make the urine less concentrated. Increased water absorption can be achieved by giving the cat a wet food (canflex / pouch) or by soaking dry kibbles in water.

It is further advised to monitor regularly for urine pH, presence of crystals, urinary tract infection and any new stones. If the urine pH is below 6.5, potassium citrate can be given to slightly increase the urine pH. The advice is to keep the specific gravity of the urine below 1.030.

With recurrent calcium oxalate stones, it is advisable to investigate whether there are underlying causes for a disturbance in the calcium balance that can possibly be treated (see appendix).

The diets we recommend for calcium oxalate urolithiasis in cats: SPECIFIC® FKD / FKW / FKW-P

SPECIFIC® Kidney Support (FKD / FKW / FKW-P) is for the prevention of recurrence of calcium oxalate stones in cats. These kidney diets are very tasty and due to the reduced protein and sodium content and the induction of an alkaline urine pH suitable for the prevention of calcium oxalate stones.

If the cat's urine pH is too low, potassium citrate can help make the urine alkaline and keep calcium and oxalate in solution. The guideline is a urine pH between 6.5 and 7.5. Starting dose 2 times 50-75 mg / kg.

The dose is a starting dose and good monitoring / adjustment is desired (pH guided, 2 weekly monitoring

For additional information including answers to SPECIFIC questions:

Visit the SPECIFIC FAQ page

Urinary Diet Resources

Urinary Diets Data Sheet

Full product data sheets are available at the SPECIFIC product information book including

Indications for each diet
Properties and rational for the composition
Ingredients
Feeding amounts
Nutrient data
Any contra indications

Click here

SPECIFIC owner website

The SPECIFIC owner web sites provide a valuable tool to help explain nutrition to your clients. With pages talking about the condition and the role nutrition plays in supporting management of those conditions and details of the individual products that you may be recommending.

If you would like to link to the SPECIFIC owner web sites, the address is www.specific-diets.co.uk/

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